Centrifuge outlet



April 12, 1966 J. JONAKIN 3,245,613

CENTR I FUGE OUTLET Filed Dec. 17, 1962 2 Sheets-Sheet l 22 FIGJ v K Z6 "20 AZ) /4 $4 fi 54 j= $zg FIG- 2 INVEN'TQR JAMES JONAKIN ATTORNEY April 1955 J. JONAKIN 3,245,613

CENTRIFUGE OUTLET Filed Dec. V17, 1962 2 Sheets-Sheet 2 INVENTOR JAMES- JONAKIN ATTORNEY United States Patent 3,245,613 CENTRlFUG-E ()UTLET James Jonakin, Simsbury, Conn, assignor to Combustion Engineering, Inc., Windsor, C0nn., a corporation of Delaware Filed Dec. 17, 1962, Ser. No. 245,293 3 (llaims. (Cl. 233-7) This invention relates to a centrifuge and particularly to the discharge outlets of the centrifuge.

In separating the coal and water in a coal slurry by means of a centrifuge it has been found that with the coal receiving edge of the coal discharge slots or openings parallel to the plane of rotation of said slots that the coal is discharged in a concentrated area of small axial extent and causes undue wear on mechanism receiving the coal from the centrifuge. This mechanism may be paddles or vanes arranged near the openings and a shroud either movable or stationary surrounding the blades and openings. The coal is discharged at a high velocity from the centrifuge and being abrasive and impinging on the blades and shroud with the high velocity in a comparatively small zone causes rapid wear in that zone. By the present invention applicant is able to distribute that wear over any desired axial length and thus distribute the wear over the substantially entire length of the vane or shroud and thus avoid the concentration and wear in a limited zone.

An object of this invention is an improved discharge for a centrifuge.

A more specific object is an arrangement of discharge slots in a centrifuge with the main working-material receiving edges of the slots having an axial component.

Further and different objects and advantages will be apparent from the following specification and the accompanying drawings in which:

FIG. 1 is a side elevation, partly in section, of a centrifuge incorporating the invention;

FIG. 2 is a sectional end view of the centrifuge of FIG. 1;

FIG. 3 is an enlarged detail view of the discharge slot, the impeller blade and the shroud;

FIG. 4 is a developed side view showing the slots and blades; and

'FIG. 5 is an enlarged side view showing the reverse screw conveyor.

In utilizing a centrifuge to separate water from a coal slurry in a pipeline coal feeding system such as shown in Tulis and Jonakin application Serial No. 159,600 filed December 15, 1961, for Drying and Burning of Pipeline Coal to which reference may be made for details of the system it has been found that the centrifuge, which may be a standard commercial article such as the centrifuge manufactured'by the Bird Machine Company of South Walpole, Massachusetts, and has rectangular discharge slots with the long edge of the slot extending circumferentially of the centrifuge drum in the Plane of rotation of that longer edge, discharges the separated coal over a comparatively narrow band of the coal receiving mechanisms thus causing undue wear of those mechanisms. Applicant has provided improved discharge slots for the centrifuge which will discharge and distribute the coal over substantially the entire axial extent of the coal receiving mechanism and thus more evenly distribute the wear.

The centrifuge comprises a drum 16 preferably in the form of a cone frustum having a barrel portion and ends, one of which is shown at 20, mounted in any suitable manner for rotation about its axis 12 by any suitable mechanism such as a motor, not shown. A coal slurry which may have any desired proportion of water and coal such as say'60% coal and 40% water is introduced into the centrifuge drum preferably continuously and in a 3,245,613 Patented Apr. 12, 196

manner well known in the art. Inside of the drum 18 and cooperating with the inner surface of the barrel portion of the drum is a screw conveyor 14 which rotates with the rapidly rotating drum 10 but at a slightly different rate so as to provide relative motion between the drum 1t) and the screw conveyor 14. Any suitable well known mechanism such as the gear box 15 may be utilized to impart such relative motion. Guide means such as axially extending vanes or ribs 18 are located on the inside surface of the drum barrel portion 19 and cooperate with the screw conveyor 14 to urge the coal axially of the drum and limit-or restrain the circumferential movement of the coal inside of the drum. The drum has a closed end 20. A casing 22 surrounds the rotating frustum and contains one or more partitions 24 dividing the easing into two discharge chambers one of which, 26, discharges solids into duct or pipe 28 and theother, not shown, discharges liquids into a suitable receiver.

The slurry discharged into the interior of the frustum collects at the large end of the frustum as it is thrown outwardly by centrifugal force. The screw conveyor 14 cooperates with the interior of the frustum to force coal from the large end toward the small end of the frustum where it is discharged through orifices 39 one side of each orifice, as shown in FIG. 5, forming a leading edge '40 with the inner surface of the drum 10. Water, being lighter than the coal will tend to stay nearer the axis of the centrifuge as the coal is centrifugally pressed, squeezed or forced against the drum and will be discharged through orifices in the large end of the frustum. The coal, which still may contain 20% or less of moisture is centrifugally discharged with considerable force from the orifices 30. Fan blades or paddles 32 are mounted on the exterior of the drum 10 preferably adjacent an orifice 3t} and are secured to the drum by any suitable means such as welding and/or braces or supports 34. A fan or blower casing 36 of generally volute section surrounds the small end of the drum ill and encloses the fan or blower blades 32 to thus convert the small end of the centrifuge drum into a blower. The fan casing 36 has an exit opening or duct 28 extending through the centrifuge casing 22. The drum Ill thus acts as a hub for the fan or blower blades 32. Air inlet opening 38 in the ends of the blower casing 36 and adjacent the drum 10 admit air'to the blower casing adjacent the coal exits 30 where the air is mixed with the filter cake, or partially dewatered slurry, being forcifully ejected through'the discharge openings 30. Reference may be made to application Serial No. 202,864 filed June 15, 1962, by Virginius Z. Caracristi for Feeding Mechanically Dried Coal Slurry From a Centrifuge Bowl for further details of thedischarge mechanism.

It will be appreciated that the dewatered coal which is being fed axially inside of the drum by the screw conveyor 14 and which has a consistency similar to that of a thick mud will, as soon as it reaches the leading edge of an orifice 3% be thrown violently outward where it will be met by a paddle 32 or be thrown against the casing 36. By making the discharge slots 30 in the form of a parallelogram with the smaller or narrow dimension of the parallelogram extending in the direction of travel of the coal relative to the centrifuge drum 10, which defines the downstream direction and is generally axial or longitudinal of the drum but may be at any desired spiral angle, and with the long dimension of the parallelogram spiralling around said drum at an acute angle to the axis or longitudinal dimension of the drum, it is possible to distribute substantially the entire amount of the discharged coal substantially equally over substantially the entire width of the fan blade 32 and the fan housing 36. The angle at which the long side of the parallelogram is arranged with respect to the longitudinal dimensionof the drum will be dictated 'by the specific requirements of the particular installation. The slots may be arranged at a smaller acute angle where it is desired to distribute the discharge over a longer axial dimension. It should be noted that because the drum is a rapidly rotatingmechanism and therefore-highly stressed the number and size of the slots is limited because of the necessity of maintaining sufficient hoop strength in the centrifuge drum 10. By arranging the parallelogram slots with the main coal receiving longer edges at an acute angle to the longitudinal dimension of the drum, it is possible to substantially equally distribute all the coal discharge over a materially greater axial dimension and provide longer coal receiving edges without materially affecting the hoop strength of the centrifuge drum over that of rectangular slots with the longer edges located in the plane of rotation of the drum. The parallelogram slots will provide a more even distribution of the coal discharge and provide a stronger structure because of the removal of less material from the drum periphery than can be provided by round discharge openings.

In the preferred embodiment shown in the drawings the ribs or serrations 18 are arranged longitudinally of the drum 10 and substantially parallel to the axis to provide substantially longitudinal or axial movement of the coal along the inner surface of the drum 1!) with only a slight if any circumferential movement imparted to the coal around the inside of the drum. With such coal movement by the conveyor 14 which, as shown in FIG. 5, traverses the leading edge 40 of the slot 3%), substantially equal amounts of coal will be received along the entire length of the leading edge 40 of the slot 30 and substantially no coal will be received along the shorter edges and the coal will thus be equally distributed throughout the axial or longitudinal component of the leading edge 40 to thus distribute the wear over substantially the entire extent of that axial component. The coal moved axially between adjacent discharge slots 30 by the conveyor 14 will remain on the interior surface of the drum 10 and be pushed longitudinally downstream of the drum and discharged in a ridge of coal downstream of the slots 30 at thelend of the conveyor screw 14. A reverse acting plow or screw conveyor is mounted on the same shaft as the screw conveyor 14 but has a thread or flight of the opposite hand so as to pick up the ridge of coal left by the screw conveyor 14 and force that coal back upstream towards the large end of the drum and toward the conveyor 14. The plow 42, which as shown in FIG. has an end 44 upstream of slot leading edge 40 has a somewhat greater pitch than the screw 14 so as to impart some circumferential'movement to the coal inside of the drum 1t and thus place this returned coal in a ridge, where itis left upstream of the slot leading edges 40 by the end 44 of the reverse screw 42, in such a circumferential position with respect to drum that a substantial portion of this returned coal will be axially aligned and upstream with respect to a slot 30 so that it will now be discharged through such slot when it is again moved axially downstream across the slot leading edge 40 by the screw conveyor 14.

It will be appreciated that if desired, a spiral motion may be imparted to the coal traveling along the inside of the drum 1t) and the slots 30 made of such a length and arranged at such an angle that the entire path of the coal will be covered by the slots and there will be very little, if any, coal left to be returned for the second or re-feeding.

It will be appreciated that due to the probability of the feed screw imparting some spiral motion to the coal that it is desirable to have the leading edge 41) of the slots 30 extend in the same general direction axially of the drum as the web of the screw impeller adjacent said leading edge. The slots will then spiral in the same general direction as the screw impeller.

I claim:

1- A centrifuge for separating coal and water from a coal slurry comprising, a drum in the form of a cone frustum rotatable about the axis of said frustum, axially extending guide vanes on the inner surface of said frustum, a screw conveyor cooperating with said vanes to feed the centrifuged coal axially of said surface, elongated circumferentially spaced discharge slots in said surface, said slots in said surface extending transversely through said drum barrel portion adjacent the downstream end of said conveyor, each slot having an elongated side forming, with the inside surface of said cone, a coal receiving edge receiving substantially all the coal fed to said slot, said edge arranged at an acute angle to said axis and spiralling in the same direction as the adjacent feed surface of said screw and receiving from said screw a substantially uniform flow of coal throughout its length, coal receiving means around said drum receiving coal centrifugally discharged outwardly from said slots and subject to abrasion therefrom, said angularly arranged coal receiving edge having an axial component substantially equal to the axial extent of said coal receiving means outside of said drum to distribute the Wear substantially equally over the axial extent of said receiving means, a reverse screw conveyor having a greater pitch than said first mentioned screw conveyor, cooperating with the interior cylindrical surface of said drum, and returning, for again feeding'to said slots by said first mentioned conveyor, coal that has been fed by said first mentioned conveyor beyond said slots.

2. A centrifuge for separating coal and water from a coal slurry comprising a drum rotatable about the longit-udinal axis of the drum, a screw conveyor rotatable about said axis inside of and relative to said drum, elongated circumferentially spaced discharge slots in the periphery of said drum adjacent the downstream end of said conveyor and receiving the centrifuged coal fed by said screw in a direction toward said slots, said slots arranged with their longer sides spiralling around said drum at an angle to the axial dimensions of said drum to discharge the coal fed by said screw over an appreciable axial distance, a second screw conveyor having a greater pitch than the first mentioned screw conveyor rotatable with said first mentioned screw conveyor inside of said drum and returning coal, which has been conveyed downstream between said slots, in the opposite direction along the inside of said drum to upstream of said slots to a position axially aligned with said slots.

3. A centrifuge for separating coal and water from a coal slurry comprising, a drum in the form of a cone frustum rotatable about the frusturn axis, a screw conveyor rotatable on said axis adjacent to, and relative to, the interior surface of said drum urging separated coal, centrifugally held against said surface, axially toward the small endwof said drum, said drum surface having axially extending means limiting circumferential movement of separated coal on said surface, said drum having a plurality of circumferentially spaced passageways extending from the interior to the exterior of said drum and having parallelogram shaped openings in the cylindrical surface of said drum adjacent said small end, the longer upstream edge of each said parallelogram shaped opening being a coal discharging leading edge traversed by said conveyor and spiralling around said drum at an angle to the axial dimension of said surface and spiralling in the same direction as said screw conveyor, coal receiving means around said drum having an axially extending surface receiving coal centrifugally discharged outwardly from said slots and subject to abrasion by said discharged coal, each of said longer upstream edges adapted to receive a substantially uniform flow of coal throughout its length to substantially uniformly distribute coal throughout its respective opening over an axial distance substantially equal to the axial extentof said coal receiving means and the shorter upstream edge of said parallelogram shaped opening extending substantially parallel to the path of travel of said coal alon the interior surface of said drum so as to receive and discharge substantially no coal.

Ritsch 2337 Smith 233-7 Millikan et a1 233-7 Smith 2337 Philipp 198-64 Peltzer 23347 X Gooch 233-7 Gooeh 2337 Lacker et a1 2337 X M. CARY NELSON, Primary Examiner.

2,528,974 2,578,456 2,600,372 References Cited by the Examiner 2 22 79 UNITED STATES PATENTS 5 2,630,906

McCelland 19s 214 Van Kirk 2337 Phillips 233 7 2,703,676 3 081 026 Landreth 2337 Wilderman 210-374 1 Wettlaufer 210369 De Mattia 2337 Jahn 2337 X ROBERT F BURNETT, Examiner. 

1. A CENTRIFUGE FOR SEPARATING COAL AND WATER FROM A COAL SLURRY COMPRISING, A DRUM IN THE FORM OF A CONE FRUSTRUM ROTATABLE ABOUT THE AXIS OF SAID FRUSTUM, AXIALLY EXTENDING GUIDE VANES ON THE INNER SURFACE OF SAID FRUSTUM, A SCREW CONVEYOR COOPERATING WITH SAID VANES TO FEED THE CENTRIFUGED COAL AXIALLY OF SAID SURFACE, ELONGATED CIRCUMFERENTIALLY SPACED DISCHARGE SLOTS IN SAID SURFACE, SAID SLOTS IN SAID SURFACE EXTENDING TRANSVERSELY THROUGH SAID DRUM BARREL PORTION ADJACENT THE DOWNSTREAM END OF SAID CONVEYOR, EACH SLOT HAVING AN ELONGATED SIDE FORMING, WITH THE INSIDE SURFACE OF SAID CONE, A COAL RECEIVING EDGE RECEIVING SUBSTANTIALLY ALL THE COAL FED TO SAID SLOT, SAID EDGE ARRANGED AT AN ACUTE ANGLE TO SAID AXIS AND SPIRALLING IN THE SAME DIRECTION AS THE ADJACENT FEED SURFACE OF SAID SCREW AND RECEIVING FROM SAID SCREW A SUBSTANTIALLY UNIFORM FLOW OF COAL THROUGHOUT ITS LENGTH, COAL RECEIVING MEANS AROUND SAID DRUM RECEIVING COAL CENTRIFUGALLY DISCHARGED OUTWARDLY FROM SAID SLOTS AND SUBJECT TO ABRASION THEREFROM, SAID ANGULARLY ARRANGED COAL RECEIVING EDGE HAVING AN AXIAL COMPONENT SUBSTANTIALLY EQUAL TO THE AXIAL EXTENT OF SAID COAL RECEIVING MEANS OUTSIDE OF SAID DRUM TO DISTRIBUTE THE WEAR SUBSTANTIALLY EQUALLY OVER THE AXIAL EXTENT OF SAID RECEIVING MEANS, A REVERSE SCREW CONVEYOR HAVING A GREATER PITCH THAN SAID FIRST MENTIONED SCREW CONVEYOR, COOPERATING WITH THE INTERIOR CYLINDRICAL SURFACE OF SAID DRUM, AND RETURNING, FOR AGAIN FEEDING TO SAID SLOTS BY SAID FIRST MENTIONED CONVEYOR, COAL THAT HAS BEEN FED BY SAID FIRST MENTIONED CONVEYOR BEYOND SAID SLOTS. 